Air charger for hydropneumatic systems



May 23, 1950 A. w. BURKS AIR CHARGER FOR HYDROPNEUMATIC SYSTEMS Filed March 11, 1946 y ZIIId/l/ll/l/fl w 7 ,1, x a. V 3 r m 0 g z M. H 1 V M #1 q. N E m 0 I H W v 6 M 7 2 Hr M 1 H U IV u A M v a nu 7 N 7 8 g 7. 6 9 1 1 1 m 1 Patented May 23, 1950 AIR CHARGER FOR HYDROPNEUMATIC SYSTEMS Arthur W. Burks, Decatur, Ill., assignor to Decatur Pump Company, Decatur, 111., a corporation of Illinois Application March 11, 1946, Serial No. 653,688

7 Claims. (01. 103--6) My invention relates to an air charger for hydro-pneumatic systems, and more particularly to an air charger for supplying air to a hydropneumatic tank in response to the pneumatic pressure requirements of the system.

The present invention relates to a novel and improved air charger mechanism for maintaining the pneumatic pressure in a hydro-pneumatic supply tank within the desired limit and is a continuation in part of my copending application Serial No. 575,693, filed February 1, 1945. This application has now issued as U. S. Patent No. 2,457,863, dated January 4, 1949. The air charger of my invention operates to supply air to the hydro-pneumatic tank, if required, whenever the pump that supplies the hydro-pneumatic tank with water is operated.

An important feature of my invention is the provision of an eductor, or aspirator, operated by the flow of water under pressure from the pump, whenever the air cushion in the tank requires replenishing, to draw atmospheric air into the air charger casing for subsequent displacement into the hydro-pneumatic tank to replace losses of air from the tank and to build up the air pressure therein to within the desired limits. A float operated valve cooperates with the eductor, or aspirator, to eliminate, with positive certainty, the possibility of any air drawn in by the eductor finding its way into the suction side of the pump, thus causing the pump to become air bound. This has been one of the objections to previous hydropneumatic Systems employing means, such as an eductor, aspirator, or Venturi nozzle, for drawing air into the system under the action of the pump.

The air charger of my invention acts each time that the pump is started up, if the water level in. the hydro-pneumatic tank is above its normal level, to draw air into the charger, and then prior to the cessation of pumping operations, or upon its cessation, to displace the charge of air from the air charger into the tank. If no air is required in the hydro-pneumatic tank, no new charge of air is delivered into the tank, but air is merely withdrawn from the tank and then subsequently expelled back thereinto. The device is thus fully automatic and requires little, if any, attention.

In the construction of the air charger of my present invention, the eductor is positioned between the connection from the pressure side of the pump to the air charger and the connection from the air charger to the suction side of the pump. At the throat zone of the eductor, the

eductor is cut away to provide a communication with the interior of the air charger casing so as to permit water to be drawn into the eductor and mixed with the stream of water flowing under pump pressure through the eductor. A float controlled valve, actuated by a float within the air charger casing in accordance with the level of water therein, closes the opening into the throat zone of the eductor when the water in the air charger casing falls below a predetermined point, so that no air can be drawn into the eductor. However, during the operation of the pump, if the level of water in the hydro-pneumatic tank is above the normal level, air is drawn in from the atmosphere to the interior of the air charger casing due to the fall of the water level therein under the aspirating eilect of the eductor. When a full charge of air has been thus drawn in and the Water level in the air charger casing has dropped to the point at which the float is no longer sufl'iciently buoyed up, the float acts to close the valve and cause water from the pressure side of the pump to flow through the opening in the throat zone of the eductor into the air charger casing and displace the air already in the casing back into the hydro-pneumatic tank.

The action of the stream of water under pump pressure through the entering nozzle of the eductor assists in holding the valve in its closed position until the pressure between the chamber and the tank is equalized. When the pump stops running, pressure on the system as a whole equalizes and the weighted portion of the valve causes it to swing open into position ready to repeat the airpumping cycle when the pump is next put into operation.

It is therefore an important object of this invention to provide an automatically operating air charger for maintaining the desired pneumatic pressure within a hydro-pneumatic tank of a water supply system, the air charger being responsive to the pumping operation when the level of the water in the tank is above normal to withdraw air from the atmosphere into the air charger casing and then to displace the air so drawn in into the hydro-pneumatic tank, the air charger including an eductor, or aspirator, the entrance nozzle of which is connected to the pressure side of the pump and the discharge nozzle of which is connected to the suction side of the pump, the throat zone being open to the interior of the air charger casing and a float control valve being provided for closing said throat zone opening after a charge of atmospheric air has been drawn into the casing, before such air can be drawn into the eductor, thereby eliminating the possibiilty of such air being drawn into the suction side of the pump with consequent lessening of the efficiency of the pump.

It is a further important object of this invention to provide an air charger, the operation of which depends upon the action of an eductor, or aspirator, actuated by the pressure discharge of water from the pump, in combination with a float controlled valve controlling an opening from the throat zone of the eductor into the air charger casing and operating to eliminate the possibility of air getting back into the suction line of the pump and destroying the prime of the pump.

It is a still further important object of this invention to provide an air charger which, in addition to it function of maintaining the desired pneumatic pressure in a hydro-pneumatic tank, is so arranged and positioned as to serve as a primer for the pump supplying the hydro-pneumatic tank but so controlled as to eliminate positively and with certainty the possibility of air getting back into the suction line of the pump and destroying its prime.

Other and further important objects of this invention will be apparent from the disclosures in the specification and the accompanying drawings.

On the drawings:

Figure l is a broken, fragmentary, vertical sectional view, partly in elevation, of an air charger embodying the principles of my invention.

Figure 2 is a sectional view taken substantially along the lines II--II of Figure 1.

The reference numeral 10 indicate generally a hydro-pneumatic tank, which, as is customary, is partially filled with water maintained under the pressure of an air cushion above the water level. Water is supplied to the hydro-pneumatic tank by a pump H, preferably of the centrifugal type, which is connected through a suction intake l2 to a water supply pipe 13. Said supply pipe l3 has a foot valve is at its lower end, which, when installed, extend into the source of water that supplies the pump H. The pump H is connected at its discharge end E5 to a pipe it that connects through a threaded opening ll formed in the lower portion of the tank wall it; with the interior of the tank i 07 The pipe i6 is branched, as at H) to provide a branch pipe 20 connected to an eductor housing 2! formed in the lower portion of an air charger casing 22. Said housing 2! is provided with a threaded opening 22a for receiving the threaded end of the branch piping 20. At its other end said housing 2! i provided with an axially aligned threaded opening 23 for receivthe threaded end of a pipe 24 constituting the upper vertical portion of the pipe l3. Said eductor housing 2! is thus connected both to the pressure side of the pump I! and also through the pipe 24 and pipe I2 to the suction side of said pump ll.

Said housing 2i houses an eductor proper, indicated generally by the reference numeral 25. The eductor proper 25 may take the form of an elongated block of metal having an entering nozzle 25, a discharge nozzle 21 and a restricted throat zone 28 therebetween. The block is formed with a V-shaped notch 29 that extends into the throat zone 28 to provide an opening from said throat zone into the interior of the air charger casing 22. A weighted valve 38 is pivotally mounted, as at 31, to the walls of said eductor block 25 and is provided with an integrally formed valve portion '32 adapted, when the valve is tilted, to overlie the throat end 33 of the discharge nozzle 21 of the eductor. The operation of said valve 30 will be more fully described hereinafter.

The eductor block 25 is positioned in the eductor housing 2! by means including a countersunk recess 34, into which a cylindrical reduced end 35 of said block projects for supporting the discharge end of the eductor. At the intake end of the eductor, the block 25 is provided with a countersunk recess 35 for receiving the end of the hollow cylindrical nut 3i. Said nut 37 is provided externally with threads 38 for engagement with the threads of the opening 22, and is also provided with tool receiving notches 39 to facilitate the threading of the nut 31 into retainin engagement in the counterbore 36 of the eductor block 25. In its assembled position, the eductor block 25 is supported in the housing 2| with its axis in alignment with the aligned axes of the threaded openings 22 and 23.

The air charger 22 is connected at it upper end through a pipe 48 with the upper part of the hydro-pneumatic tank H3. The tank end of said pipe 40 is connected to the tank through a nipple 4i and a coupling 42. Said nipple 4! serves as a ball check housing, and for this purpose is provided with a reduced bore 43, the entrance to which is controlled by a ball M retained by a pin 45 in an enlarged bore portion 45 that communicates with the interior of the tank iii. As illustrated, a conical ball seat 41 is formed between the enlarged and reduced bores 46 and 42, respectively, the ball as serving to seat against the conical seat 41 and close off the reduced bore 43 under certain conditions, as will be more fully explained hereinafter. The retaining pin 45 prevents the ball M from becoming displaced entirely but allows the ball to fall away from the conical seat 41 to open said reduced bore 43 under certain other conditions.

This arrangement of the ball check valve assembly is such as to permit the fiowof air through the fitting in either direction but prevents the flow of water from the tank H) through the assembly into the conduit 40 and "thence to the air charger 22. The flow of water in that direction is prevented by reason of the fact that the ball 44, in response to a flow of water from the tank into the enlarged bore 46, rises against and seats upon the conical seat '41, thus closing off the reduced bore 43.

The nipple 4| enters the wall of the tank Id at about the normal water level within the tank, as indicated by the letter N. The dot-dash line H indicates a level of water within the tank I?) higher than the normal water level and the reference character L indicates a levelof water lower than the normal level. The operation of the air charger will be described in connection with the different indicated levels of water within the hydro-pneumatic tank.

At the air charger end, the pipe 48 is connected to the top of the air charger casing by means of a threaded nipple 48 and a coupling 43. A float ball 50 is positioned within the air charger casing 22 for movement therein in accordance with the level of water, indicated at 5!, within said casing. The valve 30 is provided with an offset arm 52 that extends upwardly into the path of movement of the ball 50. As illustrated in Figure 1, the level of water 51 is such that the float ball 59 is in contact with the arm 52, but has not yet fallen sufficiently far to depress said arm 52 and cause the weighted valve'Sfl to tilt into closing position. The air charger casing 22 is restricted, as at 53 to provide a guide for the float ball 50 and insure the ball hitting the arm 52 as the ball drops in the casing.

An air intake valve, indicated generally by the reference numeral 54 is inserted in a Wall of the casing 22 to control the admission of air to the interior of the casing. As illustrated, the air intake valve 54 is placed in an offset wall 55 of the casing, but this particular arrangement is not essential to the operation of the intake valve. Said valve 54 comprises a fitting 56 having a threaded end 51 for threading into the offset wall portion 55, and having a cylindrical bore 58 extending therethrough. At the opening of said bore 58 into the interior of the casing 22 there is provided a ball seat 59 for receiving a ball valve 60. Said ball valve 60 is secured to the upper end of a valve stem 6| that extends freely through the bore 58, the walls of which serve as a guide therefor. The lower end of said stem BI is provided with an enlarged head 62 to limit upward movement of the ball valve and stem. Whenever the pressure within the air charger casing 22 drops below atmospheric, the ball 60 is lifted off of the ball seat 59 to admit air into said casing, while when the pressure within said casing 22 is equal to atmospheric or above atmospheric, the ball 60 is caused to seat and close off communication with the atmosphere.

The operation of the air charger will now be described.

When the pump is not running, pressure equalizes itself throughout the system. Since the air charger is below the level of the water in the tank In, the air charger chamber, indicated by the reference character C, fills completely with water. The float 59, accordingly, rises out of contact with the valve arm 52 to let the valve assume its normal, unseated position, due to its unbalanced or counter weighted construction. The foot valve 14, prior to starting up the pump II, is in closed position.

When the pump l is started, the water already in it and in the chamber C serves to prime the pump, since the air charger 22 is above the level Of the pump ll. At the startingof the pump, the suction created by the pump causes the foot valve 14 to open, as illustrated in Figure 1, and let water be drawn up through the intake pipe I3 and branch pipe I 2 into the suction side of the pump H. The water is thereupon discharged from the pump under pressure through the pipe I6 into the tank In and also through the branch pipe 20 into the eductor 25. The passage of water under pressure through the eductor 25 causes a reduction of pressure at the throat zone 28, resulting in water being drawn into the flow through the eductor from the chamber C.

If at this time the level of water within the hydro-pneumatic tank In is at its normal level, N, or at a lower level, such as that indicated at L, the ball check valve 44 will be unseated and air will be drawn in from the tank In through the line 40 into the chamber C. This is for the reason that water is being drawn from the chamber C due to the aspirating action of the eductor 25, thereby causing a reduction in pressure within said chamber C. Since, under these conditions, air can be drawn more readily from the tank through the line 40 than it can through the air intake valve 54, said valve will remain closed.

If, however, the level of water within the hydropneumatic tank In is above its normal level, say at the higher level indicated by the reference character H, the ball check valve 44 will be seated upon the conical ball seat 41 to close off passage from the tank through the pipe 40 to the chamber C. Consequently, as the water level drops in the chamber C, the air intake valve 54 will open, the ball 50 rising from its seat 59 and admitting atmospheric air into said chamber C.

During continued operation of the pump, air will continue to be drawn in through the air intake valve 54 until a point is reached at which the float 50 has dropped sufliciently to act through the valve arm 52 to close the valve 30. When this occurs, the valve portion 32 is caused to overlie the opening 33 from the throat zone of the eductor into the discharge nozzle 21.

With the valve 39 closed, as described, the entrance nozzle 26 is left open through the throat zone 28 and discharges water into the chamber C. Since the flow of water from the entrance nozzle 26 is directed against the closed valve portion 32, the continued fiow of water through said nozzle tends to hold said valve portion 32 in its closed position even after the float 50 has risen out of contact with the valve arm 52. The flow of water into the chamber C displaces the charge of air previously drawn thereinto and forces said air back through the pipe 40, past the unseated ball check 44, into the tank I0. In this way, a charge of air is forced into the tank HI each time the pump II operates, provided that the level of the water within the tank I0 is above its normal level, N.

When the pump l is stopped, the flow of water into the chamber C continues until pressures are equalized in the chamber C and in the hydropneumatic tank l0. As soon as the flow of water through the entrance nozzle 26 of the eductor ceases, the valve 30 opens. The cycle is then ready to be repeated when the pump is again started up.

It will be noted that there is no possibility during the operation of the air charger for air to get into the throat zone of the eductor and be aspirated into the stream of water flowing back through the pipes 24 and 12 into the suction side of the pump. Before the chamber C becomes completely empty of water, and therefore before the throat zone 28 can be uncovered, the ball float 59 will drop sufliciently to cause the valve 30 to close. Thereafter, the level of water within the chamber C will start to rise, so that at no time will the opening 33 from the throat zone into the discharge nozzle 21 be open while the chamber C is empty of water. Thus, one of the principal objections to the use of eductors in systems of this character is eliminated, since there can be no possibility of air getting into the suction side of the pump and. causing the pump to become air-bound.

Another important advantage of my present system is that its operation is entirely automatic. If the air cushion within the hydro-pneumatic tank I0 is sufficient so that no air is needed, no additional air is drawn in from the atmosphere and added to that in the air cushion, but air from the air cushion is drawn out temporarily and then replaced. On the other hand, if the amount of air in the air cushion in the hydro-pneumatic tank is low, every time that the pump starts up, air is drawn in from the atmosphere and forced into the tank to build up the air cushion until the amount of air pressure therein is that required for satisfactory op.- eration of the hydro-pneumatic system.

It will, of course, be understood that various details of construction may be varied through a wide range without departing from the principles of this invention and it is, therefore, not the purpose to limit the patent granted hereon otherwise than necessitated by the scope of the appended claims.

I claim as my invention:

1. In a hydro-pneumatic system including a hydro-pneumatic tank and a pump for supplying water to the tank, an air charger adapted to supply air to the tank in accordance with the level of water therein as maintained by the pump, said charger comprising a casing having an intake for connection to the pressure side of the pump and an outlet for connection to ,the suction side of the pump, an eductor connecting said intake and outlet and having a throat zone opening into said casing, a valve controlling said throat opening zone, a float in said casing controlling said valve in accordance with the height of water in said casing, and an air intake for admission of air into said casing for subsequent displacement of said air into the tank.

2. In a hydro-pneumatic system including a hydro-pneumatic tank and a pump for supply ing water to the tank, an ai charger for supplying air to the tank in accordance with the level of water therein as maintained by the pump, said charger comprising a casing for connection to the tank, an eductor for flow connection between the pressure and suction side of the pump and having a throat zone opening into said casing, a valve controlling said throat zone opening, means controlling said valve in accordance with the height of water in said casing, and an air intake for admission of air into said casing under the aspirating action of said eductor for subsequent displacement of said air into the tank.

3. In a hydro-pneumatic system including a hydro-pneumatic tank, a pump and a water supply pipe connecting the discharge side of the pump to the tank, an air charger for supplying air to the tank in response to the level of water therein as maintained by the pump, said charger comprising a casing with an opening for connection to the tank at about the normal water level therein, said opening being valve-controlled for permitting air flow therethrough in either direction and water flow only in the direction of the tank, said casing having a first flow opening for connection to the suction side of the pump, a valve-controlled air intake in said casing for admittin atmospheric air into said casing, said casing having a second fluid flow opening connected to said supply pipe and to the pressure side of the pump, an eductor connected to said first and second fluid flow openings and operative under pressure flow of Water therethrough from the pump to cause atmospheric air to be drawn into said casing, a float controlled valve for closing fluid flow through said first fluid flow opening, and a float in said casing for controlling said valve, whereby, provided the Water level in the tank is above the normal water level when the pump is started up, said float-controlled valve being at that time open, the flow of Water under pressure through said eductor draws atmospheric air into said casing for subsequent displacement there from into the tank through the valve-controlled opening adapted for connection to the tank.

4. In a hydroepneumatic system including a hydro-pneumatic tank, a pump and a discharge line from the pump to the tank to supply water thereto, an air charger adapted to supply air to the tank in response to the level of water therein as maintained by the pump, said charger comprising a casing having a valve-controlled opening ior connection to the tank at about the normal water level therein, said opening being valve-controlled for permitting air flow therethrough in either direction and water flow only in the direction of the tank, said casing having a first fluid flow opening for connection to the suction side of the pump and a second fluid flow opening connected to and directly receiving water flow from the discharge line of the pump, a valve-controlled air intake for admitting atmospheric air into the casing, an eductor connected to said first and second fluid flow openings, the eductor thus being adapted for water flow therethrough under the difierential pressure between pump intake pressure and pump discharge pressure and operative under pressure flow of water therethrough under one set oi conditions to cause atmospheric air to be taken into the said casing and under another set of conditions to cause water from said second opening for connection to the discharge line of said pump to flow through said casing and displace air therefrom out through said air flow openin for connection to said tank, a floatcontrolled valve controlling said first opening for connection to the suction side of said pump, and a float in said casing for controlling said valve to control the flow of Water through said eductor.

5. In a hydro-pneumatic system including a hydro-pneumatic tank, a valve-controlled intake pipe having an opening through which water is drawn from a water source and a pump having its intake connected to said intake pipe and its discharge to said tank, an air charger comprising a casing having a valve-controlled connection to the tank at about the normal water level therein permitting airflow therethrough in either direction and waterflow only in the direction of the tank, a valve-controlled air intake for admitting atmospheric air into said casing, an eductor in said casing having its intake nozzle connected to the discharge of the pump and its outlet nozzle connected to the pump intake, said eductor having a reduced throat intermediate said nozzles vented to the interior of said casing and being operative under pressure flow of water therethrough for causing atmospheric air to be taken into said casing through said air intake, a floatcontrolled valve coacting with the outlet nozzle at the eductor throat for controlling water flow through said eductor to said casing or to said pump intake, and a float in said casing controlling said float-controlled valve.

6. In a hydro-pneumatic system including a hydro-pnfiumatic tank and a pump for supplying water to the tank, an air charger adapted to supply air to the tank in accordance with the level of the water therein as maintained by the pump. said charger comprising a casing having a valvecontrolled opening for connection to the tank at about the normal water level therein for permitting air flow therethrough in either direction and water flow only in the direction of the tank, said casing having a fluid flow opening for connection to the suction side of said pump, a valve-controlled air intake, an eductor having its intake nozzle connected to the pressure side of the pump and its outlet nozzle discharging into said fluid flow opening for connection to the suction side of the pump, said eductor having its low pressure throatzone in fluid flow communication through said casing withsaid air intake, a float-controlled valve for controlling water flow through said eductor by coaction with the eductor outlet nozzle at the eductor throat zone, and a float in said casing operating said float-controlled valve, whereby when the water level in said tank is above about the normal water level therein and the pump is started up, air is drawn into said casing and whereby said float-controlled valve acts to close the eductor outlet nozzle when the water level in said casing is no longer sufficiently high to buoy up said float, beyond which point the flow of water through said eductor into said casing will discharge air therefrom through said valve-controlled opening adapted for connection to said tank to replenish the volume of air in said tank.

7. In a hydro-pneumatic system including a hydro-pneumatic tank and a pump for supplying water to the tank, an air charger for supplying air to the tank in accordance with the level of water therein as maintained by said pump, said charger comprising a casing, a valve-controlled opening for connection from said casing to the tank at about the normal water level therein for permitting air flow therethrough in either diree- 25 tion and water flow only in the direction of the tank, a valve-controlled air intake, an eductor having an intake nozzle connected to the disl0 charge side of the pump and an outlet nozzle discharging into the intake side of the pump, said eductor having an opening from its low pressure throat zone in fluid flow communication with said casing, a float-controlled valve coacting with the discharge nozzle at the eductor throat zone for controlling the flow of water from the eductor intake nozzle through said eductor throat opening to said casing and from the eductor intake nozzle through said outlet nozzle to the intake side of the pump, and a float in said casing for controlling said valve, whereby when the water level in the tank is above said valve-controlled connection to the tank and the pump is started up, air is drawn into said casing for subsequent displacement from said casing back to the tank.

ARTHUR W. BURKS.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,172,057 Burks Sept. 5, 1939 2,172,097 Burks Sept. 5, 1939 2,457,863 Burks Jan. 4, 1949 

